It is known that patients suffering from Repetitive Strain Injury, Rheumatoid Arthritis, Multiple Sclerosis, Strokes, head injuries with hemipareses and neuro-muscular diseases, and like diseases suffer from an alteration in the ability to physically grip an object.
The limitations of human static hand function measurement, lie in their inability to measure the hand as an integrated dynamic total system. Various instruments had been evolved to measure particular aspects of hand function such as grip-strength to the ninety-fifth percentile or stiffness within a joint such instruments permitted the demonstration of loss of grip-strength or stiffness within a joint, but did not go far enough towards demonstrating why there had been a loss of function.
The weakness of earlier instruments lay also in their inability to provide a clinical measure of hand function in the total sense. While they could be said to measure particular aspects of hand function and were therefore of use in monitoring rheumatic diseases, they were not capable of picking up the inter-relatedness of muscle, tendon and joint function and dysfunction. Such limitations reduced their usefulness as a monitor of integrated hand function.
It has long been known to measure the pressure in a compressible object as a function of time by means of chart recorders and like instruments. It is also known from Australian Patent No. 516026 (to which U.S. Pat. No. 231255 Haski et al corresponds) to provide an instrument which measures the elapsed time between the achievement of predetermined pressure values during the compression of a bladder. The apparatus disclosed in the above mentioned patent provided an instrument which enabled a medical practitioner to determine, by skilled interpretation of the numerical pressure/time data provided, the progress of treatment for a muscular disorder by ascertaining at an early date whether the patient was responding to the treatment.
Notwithstanding the improvement in clinical assessment provided by the above instrument, there exists a need to measure and assess the actual loss of function in a joint or joints in an objective and quantitative manner. For example, in some forms of medical conditions such as Repetitive Strain Injury, the symptoms experienced by the patient may in some instances be perceived mentally rather than actually experienced and the ability to objectively and quantitatively measure any loss of function would therefore greatly enhance the assessment of such persons. Similarly, a method of objectively and quantitatively measuring joint function would also assist in accident cases where one of two hands, for example, has been damaged and financial damages are to be assessed.